Combined snap and wipe acting switch

ABSTRACT

Pushbutton switch having an elongate stationary contact and a switching contact pivotally mounted with an overcenter spring to the pushbutton for rotational movement toward and away from the stationary contact. A biasing member intercouples the switching member and the pushbutton for tensioning the overcenter spring and causing linear movement of the switching contact longitudinally of the stationary contact when the pushbutton is depressed. The biasing member also biases the switching contact away from the stationary contact before switch actuation and cooperates with the overcenter spring to snap the switching contact into engagement with the stationary contact during longitudinal movement of the switching contact, the switch then making wiping contact.

United States Patent [72] Inventor Edward A. Jones Sylmar, Calif.

[2]] Appl. No. 878,444

[22] Filed Nov. 20, 1969 [45] Patented Aug. 31, 1971 [73] Assignee Control Industries, Inc.

Sylmar, Calil.

[5Q] COMBINED SNAP AND WIPE ACTING SWITCH 8/1960 Riddell ..200/67 B (UX) 3,412,225 11/1968 Rogers et al. .....200/l68 C (UX) Primary Exa miner David Smith, Jr. AltarneySpensley, Horn and Lubitz ABSTRACT: Pushbutton switch having an elongate stationary -contact and a switching contact pivotally mounted with an 2 Claims, 7 Drawing Figs.

[52] US. Cl 200/67 B, 200/159 511 nu. CL ..H0lh 13/28 [50] Field of Search..... 200/67 [56] References Cited UN lTED STATES PATENTS 2,862,083 11/1958 Bailey ..200/67 B (UX) 2,899,512 8/1959 Burch 200/67 D1 UX COMBINED SNAP AND WIPE ACTING SWITCH BACKGROUND OF THE INVENTION Prior art electric switches are generally of the slide type wherein one contact moves axially parallel to another contact, thereby resulting in a wiping contact, or of the snap acting type wherein one contact moves substantially perpendicularly to the other contact, typically under spring pressure. However, these prior art switching techniques are not without their attendant disadvantages. A wiping type contact is prone to arcing when switching any appreciable amount of current and hence is generally unsuitable for use in current switching applications due to the relatively slow making of contact. A snap acting switch is much more suitable for current switching applications due to the more positive making of contact, yet fails to provide even the slight amount of self-cleaning action of a sliding contact and hence the contacts are subject to excessive pitting and require frequent bumishing.

In both of these aforementioned prior art switching types, contact engagement occurs at the same spot on the contact surfaces upon each switch operation, as does contact disengagement, thereby resulting in contact contamination which soon degrades switching performance.

SUMMARY OF THE INVENTION The present invention is directed toward a combined snap and wipe acting switch which is self-cleaning and in which contact engagement and disengagement do not always occur at the same spots on the contact surfaces, the wiping action then resulting in efficient contact cleaning while the snap action results in a positive making and break to enable efficient high current switching.

In a presently preferred single-pole double-throw (s.p.d.t.) embodiment in accordance with the present invention concepts the stationary contacts are elongate and spaced-apart in parallel, opposing relationship and axially aligned with the direction of motion of an actuating pushbutton. The movable switch contact is of the disc shaped type and is mounted at the end of a movable switching member pivotally secured to the actuating pushbutton by means of an overcenter spring for angular movement between the stationary contacts. A biasing member intercouples the switching member and the actuating pushbutton for tensioning the overcenter spring and causing linear movement of the switching member longitudinally of the stationary contacts in response to movement of the actuating pushbutton, for biasing the movable contact in engagement with one of the stationery contacts when the actuating pushbutton is in its unactuated position, and for cooperating with the overcenter spring to cause a snap action movement of the movable contact as it is moved along the length of the stationary contacts, the overcenter spring then biasing the movable contact in engagement with the other stationary contact as the switching member movement is completed.

Thus, during the first part of switch movement a wiping of a portion of the first stationary contact occurs, followed by a snap action of the movable contact over to the second stationary contact and a wiping of that contact is again cleansed by a wiping action, positive make and break occurring due to the snap action, followed by another wiping of the the first stationary contact. Due to the longitudinal movement of the movable contact the snap action does not always occur at the identical point, and the switch contacts are self-cleansed both before and after each snap action, thereby resulting in a significant increase in contact life due to the practical elimination of contamination from arcing. The present invention switch structure lends itself to ganging in an extremely compact form wherein the sets of contacts are grouped circumferentially around a central actuating pushbutton.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a four-pole double-throw switch embodiment in accordance with the present invention;

FIG. 2 is an elevation view taken along line 22 of FIG. 1, showingthe switch with the pushbutton in an upper position;

FIG. 3 is a bottom view of the switch, showing the contact terminal arrangement;

FIG. 4 is an electrical schematic of the switch contacts;

FIG. 5 is a partial elevation view taken along the line 2--2 of FIG. 1, with the pushbutton depressed and the switch actuated;

FIG. 6 is a partial elevation view, partly cut away, viewed from a right angle to FIG. 2; and,

FIG. 7 is a partial elevation view, partly cut away, viewed from a right angle to FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawing, there is shown in FIG. 1 a perspective view of a presently preferred embodiment of a-fourpole double-throw switch in accordance with the present invention concepts. The switch is cylindrical in form and of the pushbutton type, a switch housing generally indicated by the reference numeral 20 being topped by a pushbutton 10. The four sets of switch contacts are shown schematically in FIG. 4, wherein four movable contacts 101,104,107 and 110 are associated with respective stationary contact pairs 102-103, 105106, 108-109 and 111-112. A light bulb 115 is also indicated, the bulb being mounted in the pushbutton and connected to terminals 113 and 1 14.

The physical construction of the switch and arrangement of the contacts are shown in FIGS. 2 and 3, with the pushbutton in its upper position wherein the switch is in a first condition with the switch contacts interconnected as shown in FIG. 4. In this first condition the movable contacts 101, 104, 107 and are in engagement with the respective stationary contacts 102, 105, 108 and 111. Depression of the pushbutton 10 will actuate the switch to a second condition wherein the movable contacts 101, 104, 107 and 110 are moved into engagement with the respective stationary contacts 103, 106, 109 and 112.

First considering FIG. 2, the switch housing 20 comprises a cylindrical base 21, a central insert 22 and an upper cylindrical cap 23, all of a suitable electrical insulating material and held in assemblage by an outer retaining sleeve 25. The upper surface of cylindrical base 21 defines a central depression 26 of circular cross section and a series of four circumferentially spaced depressions 27 of rectangular cross section. Into each of the rectangular depressions 27 is mounted a set of elongate stationary switch contacts, the contacts being in parallel alignment and abutting opposing faces of the rectangle. All of the stationary switch contacts are of a configuration substantially identical to the contacts 102 and 109 visible in FIG. 2, contact 109 comprising an upper contact portion 109a, extending partially across the abutting wall of rectangular depression 27, and a lower terminal portion 109b, which is narrower than the upper portion and which extends through base 21 and projects from its bottom surface to form a terminal connector.

Each of the movable contacts 101, 104, 107 and 110 has an associated contact terminal for electrical connection thereto, these terminals being respectively indicated by the reference numerals 101a, 104a, 107a and 110a. Each of these terminals is of a configuration similar to the lower terminal portions of the stationary contacts and is disposed in abutment with the radially innermost surface of a different one of depressions 27, in spaced-apart perpendicular alignment to the associated stationary contacts, and extending through base 21 to form a terminal connector, the alignment and spacing between the contact terminals being best seen from FIG. 3.

The upper cap 23 is of cylindrical tubular configuration, defining a smaller diameter upper portion 230 and a larger diameter lower portion 23b and forming between them a transversely extending annular shoulder 24. Slidably mounted within upper portion 23a is a tubular metallic sleeve 28 capped at the topby pushbutton 10 and abutting at its bottom against the upper surface of an insulating annular disc 30. As elongate insulating tube 31 is secured within sleeve 28, tube 31 extending through the center of annular disc 30, through a central passageway in the insert 22, and partially into the central depression of base 21.

The miniature light bulb 115 is mounted within a tubular metallic insert 32 secured within the upper end of sleeve 28, pushbutton being of translucent plastic for illumination by the light from bulb 115. The bulb is mounted within insert 32 by means of a snap ring 116 seated within an annular groove in the interior surface of the inset and bearing against the upwardly facing shoulder of the base of the bulb. The central contact of bulb 115 abuts on the top of a metallic rod 33 slidably mounted within tube 31, the rod 33 being spring loaded by a'coil spring 34 seated in depression 26 of base 21 and abutting against the bottom of the rod. The contact terminals 113 and 114 are mounted in base 21 and project from its bottom. Electrical connections to these terminals from the bulb 115 are made through rod 33 and through insert 32 and sleeve 28 by means not shown, in such manner that the bulb 115 will be connected to the terminals only upon depression of pushbutton 10.

Each of the movable switch contacts 101, 104, 107 and 1 10 is mounted in a substantially identical manner and will be explained with reference to contact 107, the movable contact being of an elongate U-shape and defining a button contact 120 at the lower base of the U, the button contact projecting from both major surfaces of the U as can be seen in FIGS. 6 and 7. Contact 107 is pivotally mounted to disc 30 by means of an overcenter spring 35, one end of the spring being secured to disc 30 and the other end of the spring being secured to the base of the U formed by contact 107, the spring being disposed within the space between the legs of the U. Thus, the contact 107 depends from disc 30, the contact passing through a suitable passageway in insert 22 and projecting into depression 27 in base 21 between the upper portions of stationary contacts 108 and 109.

Pivotally mounted to the underside of disc 30, by means of a pair of spaced-apart, rigid bars 37, is a pair of generally L- shaped biasing arms 40, each biasing arm being pivotally mounted by a pin 41 to a different one of the bars. Each of the arms 40 is pivotally mounted at one of its ends, the other end being hooked over the end of a different one of the legs of the U defined by the contact 107. The biasing arms 40 project outwardly away from the major surfaces of the contact 107 and extend over the upper surface of central insert 22 when the switch is in its first condition as shown in FIGS. 2 and 6. Thus, in this position, the biasing arms 40 bias the button contact 120 in engagement with the upper contact portion 108a of elongate stationary contact 108, the engagement between contacts 120 and 108 being firm due to the tensioning of the overcenter spring 35 also directly couples contact 107 to disc 30 for linear movement upwards and downward upon depression and release of pushbutton 10.

Upon depression of pushbutton 10, sleeve 28 pushes disc 30 downwards and hence moves movable contact 107 (and all the other movable contacts) downwards, the biasing of overcenter spring 35 holding button contact 120 in firm sliding engagement with the upper portion 108a of stationary contact 108. As this assemblage moves downwards the biasing arms 40 will begin to rotate due to contact with an upper edge surface of insert 22 (this upper edge surface preferably being chamfered as indicated at 38 in FIGS. 6 and 7) and an inner vertical surface of the insert as the assemblage moves farther downwards. Rotation of biasing arms 40 will cause a snap action of contact 107 due to the overcenter spring action, rotating the contact 107 toward the stationary contact 109 and snapping the other side of button contact 120 in engagement with the upper portion 109a of stationary contact 109, further downward movement of the assemblage then resulting in wiping contact as the button 120 slides longitudinally downward along the surface of contact 109. Subsequent to the snap action the tension of the overcenter spring 35 will then bias button contact 120 into firm engagement with stationary contact 109, the switch being in its second condition as shown in FIGS. 5 and 7.

The illustrated embodiment is a momentary action switch, release of pressure on pushbutton 10 resulting in upward movement of the movable contacts due to the forces exerted by spring 34 and another spring 39 positioned between disc 30 and central insert 22, and return of the switch to its first condition. Of course, through the use of well known mechanisms, the switch can be made to stay in its second condition until pushbutton 10 is again depressed.

Upon upward movement of the movable contacts and return of the switch to its first condition, the converse of the above-described action will occur. Briefly, at the initial stages of motion, the button contact wipes along the stationary contact surface 109a in a self-cleaning action. As the biasing arms 40 begin to project above the upper surface of insert 22 the tension of spring 35 will cause them to rotate, to the extent permitted by the insert 22 surfaces, until the arms rotate to a sufficient extent to cause a snap action of the overcenter spring 35, followed by a wiping movement of button contact 120 longitudinally along the upper portion 108a of stationary contact 108, the switch then being again in its first condition. The degree of rotation of the biasing arms 40 with respect to the vertical position of the movable contacts will be determined by the clearance between the biasing arms and the side surface of the central insert 22 and the degree of chamfer of the edge surface, it being presently preferred to cause snap action near the midpoint of movable contact travel in order to achieve an approximately equal wiping of each of the two stationary switch contacts in a contact set.

Electrical interconnection of each of the movable contacts with its associated contact terminal is provided by means of a thin metallic strip secured along a portion of its length to the side of the movable contact and with a projecting end portion in continual sliding contact with the associated contact terminal. As illustrated in FIGS 2 and 5, electrical interconnection between movable contact 107 and its associated contact terminal 107a is provided by a metallic strip 50 secured to the inner edge of contact 107 and having a radially inwardly projecting tip portion 51 in sliding contact with the upper portion of contact terminal 107a within depression 27.

Thus, there has been described a combined snapand wipeacting switch which not only provides a self-cleaning and longlasting switch, but also is amenable to ganging in compact configurations. Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

Iclaim: 1. A combined snap and wipe-acting switch, comprising: an elongate stationary contact; an actuating member for movement between first and second rest positions; a

a movable elongate switching member having first and second ends and an intermediate portion, defining a switching contact adjacent a first end thereof;

an overcenter spring secured at one of its ends to said actuating member and at its other end to sad intermediate portion of said switching member to pivotally secure said switching member to said actuating member for angular movement of said switching contact toward and away from said stationary contact;

a housing defining an interior cavity and defining a shoulder extending transversely of said stationary contact; and

a substantially L-shaped biasing member pivotally mounted at one end to said actuating member and secured at its other end to said switching member, the right angle comer of said L-shaped biasing means projecting over said shoulder when said actuating member is in its first rest position for biasing said switching contact-away from said stationary contact, and for contact with the edge of said shoulder as said actuating member is moved toward said second rest position to rotate said biasing member and cause a snap action movement of said switching contact into engagement with said stationary contact.

2. A combined snapand wipe-acting switch, comprising;

a first elongate stationary contact;

a second elongate stationary contact opposing said first elongate stationary contact and in substantially parallel alignment therewith;

an actuating member for movement between first and second rest positions;

a movable elongate switching member having first and second ends and an intermediate portion, defining a switching contact adjacent a first end thereof;

an overcenter spring secured at one of its ends to said actuating member and at its other end to said intermediate portion of said switching member to pivotally secure said switching member to said actuating member for angular movement of said switching contact between said first and second stationary contacts;

a housing defining an interior cavity and defining a shoulder extending transversely of said first and second stationary contacts; and

a substantially L-shaped biasing member pivotally mounted at one end to said actuating member and secured at its other end to said switching member, the right angle corner of said L-shaped biasing means projecting over said shoulder when said actuating member is in its first rest position for biasing said switching contact into engagement with said first stationary contact, and for contact with the edge of said shoulder as said actuating member is moved toward said second rest position to rotate said biasing member and cause a snap action movement of said switching contact out of engagement with said first stationary contact and into engagement with said second stationary contact. 

1. A combined snap and wipe-acting switch, comprising: an elongate stationary contact; an actuating member for movement between first and second rest positions; a movable elongate switching member having first and second ends and an intermediate portion, defining a switching contact adjacent a first end thereof; an overcenter spring secured at one of its ends to said actuating member and at its other end to sad intermediate portion of said switching member to pivotally secure said switching member to said actuating member for angular movement of said switching contact toward and away from said stationary contact; a housing defining an interior cavity and defining a shoulder extending transversely of said stationary contact; and a substantially L-shaped biasing member pivotally mounted at one end to said actuating member and secured at its other end to said switching member, the right angle corner of said L-shaped biasing means projecting over said shoulder when said actuating member is in its first rest position for biasing said switching contact away from said stationary contact, and for contact with the edge of said shoulder as said actuating member is moved toward said second rest position to rotate said biasing member and cause a snap action movement of said switching contact into engagement with said stationary contact.
 2. A combined snap- and wipe-acting switch, comprising: a first elongate stationary contact; a second elongate stationary contact opposing said first elongate stationary contact and in substantially parallel alignment therewith; an actuating member for movement between first and second rest positions; a movable elongate switching member having first and second ends and an intermediate portion, defining a switching contact adjacent a first end thereof; an overcenter spring secured at one of its ends to said actuating member and at its other end to said intermediate portion of said switching member to pivotally secure said switching member to said actuating member for angular movement of said switching contact between said first and second stationary contacts; a housing defining an interior cavity and defining a shoulder extending transversely of said first and second stationary contacts; and a substantially L-shaped biasing member pivotally mounted at one end to said actuating member and secured at its other end to said switching member, the right angle corner of said L-shaped biasing means projecting over said shoulder when said actuating member is in its first rest position for biasing said switching contact into engagement with said first stationary contact, and for contact with the edge of said shoulder as said actuating member is moved toward said second rest position to rotate said biasing member and cause a snap action movement of said switching contact out of engagement with said first stationary contact and into engagement with said second stationary contact. 